Method of cleaning surfaces



Aug. 5, 1952 w, c UHR] 2,605,596

METHOD OF CLEANING SURFACES Filed Nov. 10, 1949 William C.Uhri

INVENTOR.

AT TOR HEY.-

Patented Aug. 5, 1952 UNITED stars FATE .7 2.605.596 person or CLEANING simmers:

William 0. Uhri, Miiwaukeavvis- ApplicationNovember 10, rs4aseriailve.126,50?

' 7'Glairns. (01. 51-2 2) This invention relates in general to a method of cleaning surfaces, particularly metal surfaces, of oils, dirt, scale and rust by employing air as the motive power for producinga substantially finely atomized flat stream of slurry, comprising water, a detergent, and an abrasive.

The novelty of thev invention resides in providing an improved method of cleaning by utilizing a thin, fiat, fan-shaped stream of cleaning slurry, of a shape such as may be produced by the apparatus of applicants copending application, Serial No. 123,258. The particular shape of the delivered stream of cleaning slurry incorporating an abrasive is new, as far as is known, and the method of forming the stream and its employment in cleaning surfaces is likewise new.

I-Ieretofore various methods have been used to clean metal surfaces by using an abrasive carried either by water or air as the motivating fluid. For instance, Eppler, in Patent No. 2,380,738 claims a method of generating a dry sand blast and adding a rust inhibitor immediately prior to contact of the blast with the surface to be cleaned; Swenarton in Patent; No. 2,387,193 claims a method projecting, a highpressure blast of air and sand against a metal surface while simultaneously causing a veryfine mist-like spray of an aqueous liquid (rust inhibitor) to intersect such blast in mid-air, prior to its impact with the surface to be blasted; and Smith, in Patent, No. 2,040,715,.c1aims, a method of blast-treating a surfaceby discharging at high pressures a confined stream of liquid substantially unmixed with solids and externally coated with a granular abrasive. This invention, on the other hand, deals with a method of cleanin surfaces in which the cleaning slurry is projected preferably at an angle against the surface to be cleaned in a finely atomized state, and in which the stream of cleaning slurry may be utilized to lift the particles of oil, dirt, and rust from a surface, rather than blast them oif, such as results from direct impingement in the methods above discussed.

The invention has for its object the, provision of a method for cleaning surfaces by employing a thin, flat, edgewise diverging jet of cleaning slurry at high velocity in a substantially complete state of atomization.

Fig. 1 of the accompanying drawing is a perspective view of the movement of material involved in the method of the present invention.

Extensive experimental work undertaken prior to filing my application for letters patent for a washer gun, which resulted in Patent No.

2,007,029, disclosed'that a finely'atomized stream of air and watrofa particular shape, was. very efficaciousin removingdirt and dust that had beentrampedinto the pitted surface of concrete and baked by the sun. Washingwith an ordinary stream'ofhig'h pressure water was useless.

It, was discovered that the 'minute particles of water, due to the high degree-of atomization, wouldpenetrate' between the particlesofdirt and lift them away from'the surface to which. they were adhered. Tests disclosed that when: large particles of water were used in an attempt to clean the dirt encrusted article, the large particles. of water would'impinge upon the particles of dirt, and rebound therefrom-,- without causin an eifectual separation off'the dirt from the article. The washergu'n of my above mentioned patent provided a device that solved this problem. l

It then became apparent that there was a need inthe so-called wetblasting art for rapidly removing tenaciously adhering oil, grease, rust and scale from various surfaces, particularly metal surfaces. The problem facing the art was the production of a finely atomized fiat, thin stream of slurry containing an abrasive and to discharge this stream of slurry at high velocity. The use of an ordinary circular, orconicalshaped stream of" water orair, carrying abrasive, and being impinged against a surface to be cleaned, as practiced generally, is costly in that too much time is consumed in performing the cleaning operation because the mixture directed at the workpiece is substantially unmixed, in the manner contemplated by this invention.

The invention utilizes high-velocity air as the motive power for the cleaning slurry, and inasmuch as the slurry should be discharged in a finely atomized state, it is necessary tov provide for substantially complete atomization of the slurry. This is accomplished by first substantially completely enveloping a thin, flat, fanshaped stream of air or motive fluid i traveling at high velocity with a slurry 2, comprising water, a detergent and a suitable abrasive and moving in a direction substantially normal to the air. The direction of travel of the slurry is changed by the chamber 3 disposed between the inner nozzle 4 and the outer nozzle 5 so that the slurry is caused to surround the stream of air. The air will carry the fairly coarse slurry mixture along with it until discharged, and unless provision is made'to change the consistency of the coarse mixture it will not be discharged in the finely atomized state, as desired. This is accomplished during passage of the primary coarse mixture through the outer nozzle where the upper and lower walls of the nozzle converge slightly toward the outer end of the nozzle as disclosed in applicants co-pending application Serial No. 123,258, thereby in effect momentarily choking passage of the mixture to efiect substantially complete atomization of the same. The outer nozzle isofsubstantially the same shape as the inner nozzle in that it too, provides for delivery of a thin, {flat fan-shaped stream. In fact, the outer nozzle is substantially a straightline continuation of the inner nozzle.

It is preferable that the stream of slurry mixture be directed through the cleaning or blasting device in a manner such that its path of travel will meet the path of travel of the motive fluid in a plane that is substantially normal or transverse to that of the motive fluid. There may be some variance betweenthe directions of travel of the motivejfluid andslurry mixture but the nearer the -respective paths -,of travel parallel one anotherthe-lessmixing will occur.

Tests have disclosed that'if -a;flnely atomized thin, flat fan-shaped streamof abrasive slurry is discharged at an angle, preferably about 60 from the horizontal, and at high velocity, such as about 500 feet per second or, in excess thereof, the tiny particles of the abrasive slurry will penetrate between the largerparticles of rust, scale, and

dirt and will lift the same from the surface being treated. V

It will be understood that in use, the gun may be fixed and the surface tobe cleaned may be moved relative thereto, or the cleaning gun may be portable to traverse the workpiece.

Experimental tests; on sheet steel cnameling stock, have disclosed that with the cleaning gun mounted a distance of six inches from the workpiece, a strip 3% inches in width-may be satisfactorily cleaned at a rate of 20 feetper, minute, and at '9 inches distance at 5% inch strip may be cleaned satisfactorily at a rate of feet per minute. This indicates a cleaning rate of about 7 square feet per minute'for the particular abrasive mix employed. y

By incorporating a suitable detergent in the slurry mix, any oil or-grease on thesurface to be cleaned may be quickly removed therefrom. The use of a wet cleaning slurry reduces the dust problem with its likelihood of silicosis,and of particular importance, is that recovery of the abrasive material is greatly increased, due to the fact that the abrasive incorporated in the slurry mix is of asubstantially fine mesh, and when combined with water .and a detergent, the cushioning effect of the liquid minimizes abrasive particle breakdown to a substantial degree.

Various embodimentsjof the invention may be employed within the scope of the accompanying claims. I

I claim: 7

1. The method of cleaning a surface which comprises discharging at high velocity, a thin, flat edgewise divergingjjet of gaseous fluid into a stream of cleaning slurry which is moving in a direction substantially normal to the direction of movement of the gaseous fluid to cause substantial envelopment'of saidfluid by said slurry, immediately forming the mixture of gaseous fluid and slurry into a second thin, flat edgewise diverging jet, confining said second mixture jet for a sufficient time while simultaneou sly progressively decreasing I the a thickness thereof to permit ,substantial atomization of the same, and

4 thereafter freeing the atomized mixture at high velocity against the surface to be cleaned.

2. The method of cleaning a surface with a flat stream of substantially finely atomized cleaning slurry at high velocity which comprises substantially enveloping a thin, flat edgewise diverging jet of gaseous fluid with an abrasive slurry which is moving in a direction substantially normal to the direction of movement of the gaseous fluid to form a mixture of said fluid and slurry, controlling the width and progressively decreasing the thickness of said mixture for a sufficient time to permit substantial atomization of said mixture, and thereafter discharging said atomized mixture at high velocity against the surface to be cleaned.

3. The method of cleaning a surface which comprises discharging at high velocity a thin, flat edgewise diverging jet of gaseous fluid which is being propelled in a-selected direction into a stream of cleaning slurry moving in a direction substantially transversely to. the direction of movement of the gaseous fluid to cause substantial envelopment of the fluid by the slurry, immediately forming a mixture of the gaseous fluid and slurry into a second thin, flat edgewise diverging jet, confining said second mixture jet of fluid and slurry for a sufficient time while simultaneously progressively decreasing the thickness thereof to permitsubstantial atomization of the same and thereafter increasing the rate of movement of the mixture by discharging the same in a stream of increasing horizontal divergenceand relatively narrow vertical thickness against the surface to be cleaned. I I

i. The method of-cleaning a, surface with a flat stream of substantially finely atomized cleaning slurry at high velocity which comprises substantially enveloping a thin, flat edgewise diverging jet of gaseous fluid with .an abrasive slurry which is moving in a direction substantially normal to the direction of movement of the gaseous fluid to form a mixture of said fluid and slurry, controlling the width and progressive- 1 1y decreasing the thickness of said mixture for a sufflcient time to permit substantial atomization of sa d mixture, and thereafter discharging said atomized mixture at high velocity against the surface to be cleaned at an angle of approximately '60 degrees thereto.

. 5. The method of cleaning a surface with a flat stream of substantiallyfflnely atomized cleaning slurry at high velocity which comprises substantially enveloping a thin, flat edgewise diverging jet of. gaseous fluid with an abrasive slurry which i moving in a direction substantially normal to the direction of movement of the gaseous fluid to form a mixture of said fluid and slurry, controlling the width and progressively decreasing the thickness of said mixture for a suflicient time to permit substantial atomization of said mixture, and thereafter discharging said atomized mixture at high velocity against the surface to be cleaned in excess of 500 feet per second and at an acute angle to the surface.

6. The method of cleaning a surface with a flat stream of substantially finely atomized cleaning slurry at high velocity which comprises substantially enveloping a thin, flat edgewise diverging jet of gaseous fluid with an abrasive slurry which is moving in a direction substantially normal to the direction of movement of the gaseous fluid to form a mixture of said fluid and slurry, controlling the width and progressively decreasing the thickness of said mixture cess of 500 feet per second.

'7. The method of cleaning a surface which comprises substantially enveloping a thin, fiat edgewise diverging jet of gaseous propellent fluid traveling in a selected direction with a stream of slurry mixture traveling in a direction transverse to that of the fluid, immediately forming a second thin, flat edgewise diverging jet of the fluid and slurry mixture, confining the second jet for a sufficient time while simultaneously progressively decreasing the thickness thereof to permit substantially complete atomization of the fluid and slurry and thereafter increasing the velocity of the atomized mixture by releasing the same against the surface to be cleaned in a jet of substantially the same shape as said previously formed jets.

WILLIAM C. UHRI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 252,979 Tilghman et a1. Jan. 31, 1882 2,039,938 Schultz May 5, 1936 2,462,480 Eppler Feb. 22, 1949 2,504,301 Cassin Apr. 18, 1950 FOREIGN PATENTS Number Country Date 51,339 Austria Dec. 27, 1911 676,491 Franc Feb. 24, 1930 

